1. Field of the Invention
This invention relates to methods of forming relatively-stable, texturized, discontinuous coating of adhesion sites on the surfaces of metallic members for use in the manufacture of plastic-coated metallic members, and articles produced thereby; and, more particularly, to methods of applying a coating of unplasticized plastic particles onto at least a portion of a metallic member and causing controlled melting and degradation of at least the portions of the particles contacting the surface of the member to form relatively-stable adhesion sites on the metallic member which may be used to place a plastic coating on the particle-coated portion of the metallic member having a controlled adhesion to the adhesion sites and to exposed, interdisposed areas of the surface on the metallic member.
2. Prior Art and Technical Consideration
Insulated, electrical conductors, such as those employed in telephone installations, are often subjected to outdoor use or to conditions that expose the insulation to the deteriorating influences of light, weather, and possibly abrasion. With respect to telephone drop wire, which is the familiar black overhead wire comprised of two, parallel, spaced conductors that brings telephone service from the telephone pole to the home, it was customary to enclose the conductors with an extruded insulating covering.
Although such protective insulative coverings have been in widespread use for many years and have proven satisfactory from most standpoints, there was a long felt desire to develop an alternative, less expensive, insulation. Such an alternative was developed and is claimed in E. J. George et al. Pat. 3,935,369 which issued on Jan. 22, 1976 and is incorporated by reference herein.
As disclosed in that patent, any alternative covering must have specific properties to fill the requirements of this type of wire. For example, it is important that the plastic-covered drop wire have an insulating material which has adequate properties to withstand exposure to the elements, as well as adequate low temperature flexibility, impact-resistance, and abrasion-resistance. Portions of the wire adjacent to each end thereof are inserted into a metallic clamp. One of the clamps is attached to a subscriber's premises and the other one to a telephone pole prior to the electrical connection of the drop wire to wiring run between the insides of the subscriber's premises and aerial distribution cables, respectively.
At both the subscriber end and the pole end of the drop wire, the retention of the drop wire in engagement with the clamps is effected by reactive forces exerted by the clamps on the insulation. If this is not transferred from the insulation to the conductors by the adhesion herebetween, the insulation may pull from the conductors and the entire weight of the drop wire would be held by the terminal connections. This may very well lead to a disconnection of the circuit. On the other hand, if the adhesion between the composition and the conductors is too great, there may be problems in attempting to strip the covering from the conductors. Too great an adhesion could require an excessive scraping activity that could remove some of the metallic material from the surface portions of the conductors thereby increasing the electrical resistance and changing the conductivity thereof. Excessive scraping also unduly reduces the cross-sectional area of the wire or knicks it thereby reducing the strength properties of the wire to the detriment of its weight-supporting capability.